Surface-enhanced Raman Scattering Applications Research Articles

Highly ordered TiO2 nanotube films photo-decorated with Ag nanoparticles as SERS platforms: Relationship between morphology and enhancement

In this work, we synthesized TiO2 nanotube films (TiO2-NTFs) photo-decorated with Ag nanoparticles for their application in Surface-Enhanced Raman Scattering. In situ growth of Ag nanoparticles was performed through the exposure of anodic TiO2-NTFs to UVC radiation following their pretreatment in an AgNO3 aqueous solution. High nanoparticle surface densities, with uniform coverage on the film surface, and controllable size, were prepared by regulating the UVC exposure time and AgNO3 concentration. Ag nanoparticles nucleation and growth also take place along the tubes, including at the bottoms. The evidence obtained also indicates that a high enough AgNO3 concentration inhibits the well-known water-assisted crystallization mechanism, typically promoted when TiO2-NTFs are exposed for prolonged times in aqueous media. The performance of the photo-decorated films in Surface-Enhanced Raman Scattering shows that the presence of Ag nanoparticles plays a key role, and both the nanoparticle surface density and size must be regulated to promote a large number of hot-spots.

Reusable Wrinkled Nanoporous Silver Film Fabricated by Plasma Treatment for Surface-Enhanced Raman Scattering Applications.

A nanoporous silver film (npAgF), a promising structure for surface-enhanced Raman spectroscopy (SERS), can be fabricated by using successive O2 and Ar plasma treatments on a planar silver film. The common dealloying method for producing an npAgF involves annealing at high temperatures to produce an alloy film, as well as harsh etching using corrosive chemicals. By contrast, the plasma-based method can be applied directly to various functional substrates to produce more sophisticated npAgF structures. Herein, we report a facile fabrication method for a wrinkled npAgF (w-npAgF) for SERS applications using a thermally contractible polystyrene substrate. The w-npAgF had 3D wrinkles of the nanoporous structure and showed approximately 8 times higher SERS enhancement than did the flat npAgF. Moreover, the w-npAgF could be reused for multiple SERS measurements of different molecules by mild O2 and Ar plasma treatments after each use, in which the O2 plasma effectively removed the adsorbed organic molecules and the Ar plasma reduced silver oxide to pristine silver for subsequent SERS measurements. The wrinkled nanoporous structure was maintained after multiple mild plasma treatments for reuse. The simplicity of plasma-based fabrication and high sensitivity of w-npAgFs are promising features for the green production of low-cost and reusable 3D SERS substrates.

Self-Assembly of Silver Nanowire Films for Surface-Enhanced Raman Scattering Applications.

The development of SERS detection technology is challenged by the difficulty in obtaining SERS active substrates that are easily prepared, highly sensitive, and reliable. Many high-quality hotspot structures exist in aligned Ag nanowires (NWs) arrays. This study used a simple self-assembly method with a liquid surface to prepare a highly aligned AgNW array film to form a sensitive and reliable SERS substrate. To estimate the signal reproducibility of the AgNW substrate, the RSD of SERS intensity of 1.0 × 10-10 M Rhodamine 6G (R6G) in an aqueous solution at 1364 cm-1 was calculated to be as low as 4.7%. The detection ability of the AgNW substrate was close to the single molecule level, and even the R6G signal of 1.0 × 10-16 M R6G could be detected with a resonance enhancement factor (EF) as high as 6.12 × 1011 under 532 nm laser excitation. The EF without the resonance effect was 2.35 × 106 using 633 nm laser excitation. FDTD simulations have confirmed that the uniform distribution of hot spots inside the aligned AgNW substrate amplifies the SERS signal.

Dual Function of 4-Aminothiophene in Surface-Enhanced Raman Scattering Application as an Internal Standard and Adsorbent for Controlling Au Nanocrystal Morphology.

The sensitivity and quantitative accuracy of surface-enhanced Raman scattering (SERS) are the main factors that restrict its application. Here, novel Au nanoscale convex polyhedrons (Au NCPs) were designed and fabricated to solve these problems via an embedded standard, including eight pods and six small protrusions. Spherical Au seeds regrew into different sizes of Au NCPs with a face-centered cubic structure. This morphology is due to the dual mechanism of the 4-aminothiophene (4-ATP) molecule that serves as an internal standard and a surface ligand regulator combined with the regulatory role of hexadecyl trimethyl ammonium chloride. The results show that Au NCPs were enclosed by high-index {12 9 1} facets, which greatly improved the local plasma resonance and reduced the lowest SERS detectable concentration of pyrene in standard seawater to 0.5 nM. An effective reference was produced by embedding 4-ATP with a relative standard deviation value less than 2.97% (in the same batch) and 3.92% (between different batches). Our research offers a new strategy for morphological regulation of metal nanocrystals, which is useful for the preparation of highly sensitive SERS substrates and trace analysis.

Optimization Temperature Programming of Microwave-Assisted Synthesis ZnO Nanoneedle Arrays for Optical and Surface-Enhanced Raman Scattering Applications.

This study used a rapid and simple microwave-assisted synthesis method to grow ZnO nanoneedle arrays on the silicon substrate with the ZnO seed layer. The effects of reaction temperature and time on the lengths of ZnO nanoneedle arrays were investigated. The appropriate temperature programming step can grow the longer ZnO nanoneedle arrays at the same reaction time (25 min), which is 2.08 times higher than without the temperature programming step. The geometry of the ZnO nanoneedle arrays features a gradual decrease from the Si substrate to the surface, which provides an excellent progressive refractive index between Si and air, resulting in excellent antireflection properties over an extensive wavelength range. In addition, the ZnO nanoneedle arrays exhibit a suitable structure for uniform deposition of Ag nanoparticles, which can provide three-dimensional hot spots and surface active sites, resulting in higher surface-enhanced Raman scattering (SERS) enhancement, high uniformity, high reusability, and low detection limit for R6G molecule. The ZnO/Ag nanoneedle arrays can also reveal a superior SERS-active substrate detecting amoxicillin (10-8 M). These results are promising for applying the SERS technique for rapid low-concentration determination in different fields.

Recent Advances in Agglomeration Detection and Dual-Function Application of Surface-Enhanced Raman Scattering (SERS)

Surface-enhanced Raman scattering (SERS) has been widely utilized in early detection of disease biomarkers, cell imaging, and trace contamination detection, owing to its ultra-high sensitivity. However, it is also subject to certain application restrictions in virtue of its expensive detection equipment and long-term stability of SERS-active substrate. Recently, great progress has been made in SERS technology, represented by agglomeration method. Dual readout signal detection methods are combined with SERS, including electrochemical detection, fluorescence detection, etc., establishing a new fantastic viewpoint for application of SERS. In this review, we have made a comprehensive report on development of agglomeration detection and dual-function detection methods based on SERS. The synthesis methods for plasmonic materials and mainstream SERS enhancement mechanism are also summarized. Finally, the key facing challenges are discussed and prospects are addressed.

Carbaryl Pesticide Determination in Food Matrices by the Application of Surface-Enhanced Raman Scattering (Sers) AU Nano Gap Substrates in Conjunction with Chemometrics

Carbaryl Pesticide Determination in Food Matrices by the Application of Surface-Enhanced Raman Scattering (Sers) AU Nano Gap Substrates in Conjunction with Chemometrics

Fabrication of Au-Nanoparticle-Decorated Cu Mesh/Cu(OH)2@HKUST-1 Nanorod Arrays and Their Applications in Surface-Enhanced Raman Scattering

Here we report a simple fabrication method for large-scale hybrid surface-enhanced Raman scattering (SERS) active substrates composed of Au-nanoparticle-decorated three-dimensional (3D) Cu(OH)2@HKUST-1 (Cu3(btc)2, H3btc = 1,3,5-benzenetricarboxylic acid) nanorod arrays on a woven Cu mesh (Cu mesh/Cu(OH)2@HKUST-1@Au). Cu(OH)2 nanorods were first obtained from a simple in situ chemical engraving Cu mesh and then utilized as self-sacrificing templates to achieve HKUST-1 nanocube-assembled nanorods; finally, Au nanoparticles (Au NPs) were sputtered onto the Cu(OH)2@HKUST-1 nanorods. Due to the large surface area, the three-dimensional Cu mesh/Cu(OH)2@HKUST-1 nanorods could load high-density Au NPs and capture target detection molecules, which is beneficial to the formation of a strong electromagnetic field coupling between Au NPs, and provides abundant “hot spots” for a sensitive and uniform SERS effect. Using the Cu mesh/Cu(OH)2@HKUST-1@Au nanorod arrays as the SERS substrate, 10−9 M Rhodamine 6G and 10−8 M 4-aminothiophenolcan were identified. To verify their practical application, the fabricated arrays were employed as SERS substrates for the detection of thiram, and 10−8 M thiram could be recognized. The hybrid SERS substrates show potential applications in the field of environmental pollutant detection and this is of great significance to the sustainable development of the environment.

Plasmonic effect of bimetallic TiO2/Al2O3 nanoparticles in tellurite glass for surface-enhanced Raman scattering applications

Understanding the surface plasmon resonance (SPR) assisted spectroscopic properties of the glasses via the incorporation of the bimetallic nanoparticles (NPs) is a prerequisite for the surface-enhanced Raman scattering (SERS) applications. The texture, structures, and optical traits of melt-quenched synthesized Er3+-doped tellurite glasses were modified by incorporating bimetallic TiO2/Al2O3 NPs. The as-quenched samples were characterized using diverse techniques, where the X-ray diffraction (XRD) analyses confirmed their amorphous nature. The surface roughness of the glass was improved from 6.1 nm (TZNETi glass) to 9.3 nm (TZNETiAl0.6 glass). The SPR bands of the bimetallic TiO2/Al2O3 NPs were probed at 554 nm and 827 nm. The photoluminescence (PL) intensity enhancement was evidenced due to the NPs SPR-mediated strong local field effect and energy transfer between the metallic NPs and Er3+ ions. The amplification in the Raman intensity due to the NPs SPR-mediated enhanced electromagnetic field contribution. The proposed glass system may be beneficial as substrate for the SERS applications.

Applications of Surface-Enhanced Raman Scattering in Biochemical and Medical Analysis.

In this mini-review, we briefly describe certain recently developed applications of the surface-enhanced Raman spectroscopy (SERS) for determining various biochemically (especially medically) important species from ones as simple as hydrogen cations to those as complex as specific DNA fragments. We present a SERS analysis of species whose characterization is important to our understanding of various mechanisms in the human body and to show its potential as an alternative for methods routinely used in diagnostics and clinics. Furthermore, we explain how such SERS-based sensors operate and point out future prospects in this field.

Application of Surface-enhanced Raman Scattering Based onNano-signal Tags in Pathogen Detection

Application of Surface-enhanced Raman Scattering Based onNano-signal Tags in Pathogen Detection

Synthesis and deposition of Silver nanostructures on the silica microsphere by laser-assisted photochemical method for SERS applications

The homogeneous distribution of nano-metallic structures on the surface-enhanced Raman (SERS) substrates plays an important factor for high-sensitive Raman scattering measurement. In this paper, we present a low-cost laser-assisted photochemical method for making a SERS probe based on silver nanostructures, which are one-timely synthesized nano-silver structures, homogeneously deposited on silica microsphere surfaces. Achieved SERS-activity substrates with a homogeneous distribution of Ag-nanostructures are verified by a mapping technique on the surface of Ag-coated microsphere for the detection of low concentration of Rhodamine 6G in aqueous solutions in a range of 10-4-10-9M. The obtained results show that a SERS microsphere probe has a good repetition of SERS-activity in any space of sensing area, and large potential for application in a biochemical sensing technique. Full Text: PDF ReferencesY. Chen et al., "Interfacial reactions in lithium batteries", J. Phys. D: Appl. Phys. 50, 02510 (2017). CrossRef T.B. Pham, H. Bui, H.T. Le, V.H. Pham, "Characteristics of the Fiber Laser Sensor System Based on Etched-Bragg Grating Sensing Probe for Determination of the Low Nitrate Concentration in Water", Sensors 17, 0007 (2017). CrossRef X. Wang, O.S. Wolfbeis, "Fiber-Optic Chemical Sensors and Biosensors (2013–2015)", Anal. Chem. 88, 203 (2016). CrossRef R. Wang, K. Kim, N. Choi, X. Wang, J. Lee, J.H. Joen, G. Rhie, J. Choo, "Highly sensitive detection of high-risk bacterial pathogens using SERS-based lateral flow assay strips", Sens. Actuators B-Chem. 270, 72 (2018). CrossRef H. Zhang et al., "Determination of Pesticides by Surface-Enhanced Raman Spectroscopy on Gold-Nanoparticle-Modified Polymethacrylate", Anal. Let. 49, 2268 (2016). CrossRef L. Chen, H. Yan, X. Xue, D. Jiang, Y. Cai, D. Liang, Y.M. Jung, X.X. Han, B. Zhao, "Surface-Enhanced Raman Scattering (SERS) Active Gold Nanoparticles Decorated on a Porous Polymer Filter", Appl. Spectrosc. 71, 1543 (2017). CrossRef A. Matikainen, T. Nuutinen, P. Vahimaa, S. Honkanen, "A solution to the fabrication and tarnishing problems of surface-enhanced Raman spectroscopy (SERS) fiber probes", Sci. Rep. 5, 8320 (2015). CrossRef J. Zhang, S. Chen, T. Gong, X. Zhang, Y. Zhu, "Tapered Fiber Probe Modified by Ag Nanoparticles for SERS Detection", Plasm. 11, 743 (2016). CrossRef W. Xu et al., "A Dual-Butterfly Structure Gyroscope", Sensors 17, 467 (2017). CrossRef K. Setoura, S. Ito, M. Yamada, H. Yamauchi, H. Miyasaka, "Fabrication of silver nanoparticles from silver salt aqueous solution at water-glass interface by visible CW laser irradiation without reducing reagents", J. Photochem. Photobio. A: Chem. 344, 168 (2017). CrossRef K. Liu, Y. Bai, L. Zhang, Z. Yang, Q. Fan, H. Zheng, Y. Yin, C. Gao, "Porous Au–Ag Nanospheres with High-Density and Highly Accessible Hotspots for SERS Analysis", Nano Lett. 16, 3675 (2016). CrossRef Z. Huang, X. Lei, Y. Liu, Z. Wang, X. Wang, Z. Wang, Q. Mao, G. Meng, "Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application", ACS Appl. Mater. Interfaces 7, 17247 (2015). CrossRef

Understanding the Role of Metal-Organic Frameworks in Surface-Enhanced Raman Scattering Application.

Metal-organic frameworks (MOFs), built from organic linkers and metal ions/clusters, have emerged as highly promising materials for wide applications. Combining highly porous crystalline MOFs with the surface-enhanced Raman scattering (SERS) technique can achieve unprecedented advantages of high selectivity, high sensitivity, and expedience in analysis and detection. In this critical review, the aim is to present a comprehensive review of recent advances in understanding of the roles of MOFs in MOF-SERS systems, particularly their structure-to-property correlation. Key examples are selected from representative literature to illustrate critical concepts and the MOF-based property-dependent applications are particularly emphasized. Finally, the barriers, future trends, and prospects for further advances in MOF-SERS platforms are also discussed.

Metal Nanoparticles-Enhanced Biosensors: Synthesis, Design and Applications in Fluorescence Enhancement and Surface-enhanced Raman Scattering.

Metal nanoparticles (NP) that exhibit localized surface plasmon resonance play an important role in metal‐enhanced fluorescence (MEF) and surface‐enhanced Raman scattering (SERS). Among the optical biosensors, MEF and SERS stand out to be the most sensitive techniques to detect a wide range of analytes from ions, biomolecules to macromolecules and microorganisms. Particularly, anisotropic metal NPs with strongly enhanced electric field at their sharp corners/edges under a wide range of excitation wavelengths are highly suitable for developing the ultrasensitive plasmon‐enhanced biosensors. In this review, we first highlight the reliable methods for the synthesis of anisotropic gold NPs and silver NPs in high yield, as well as their alloys and composites with good control of size and shape. It is followed by the discussion of different sensing mechanisms and recent advances in the MEF and SERS biosensor designs. This includes the review of surface functionalization, bioconjugation and (directed/self) assembly methods as well as the selection/screening of specific biorecognition elements such as aptamers or antibodies for the highly selective bio‐detection. The right combinations of metal nanoparticles, biorecognition element and assay design will lead to the successful development of MEF and SERS biosensors targeting different analytes both in‐vitro and in‐vivo. Finally, the prospects and challenges of metal‐enhanced biosensors for future nanomedicine in achieving ultrasensitive and fast medical diagnostics, high‐throughput drug discovery as well as effective and reliable theranostic treatment are discussed.

Synthesis and In-Depth Study of the Mechanism of Silver Nanoplate and Nanodecahedra Growth by LED Irradiation for SERS Application

Silver nanodecahedra and nanoplates were successfully fabricated using a simple solution method, where silver nitrate (AgNO3) was reduced with sodium borohydride (NaBH4) at melting ice temperature. Green light-emitting diode (green LED, wavelength λG = 520 nm) was irradiated into the reaction system to control the morphology of the product. The synthetic procedure was a combination of two processes including the formation of silver seeds and subsequent photomediated crystal growth. This article also presents a mechanism study of the photomediated growth of silver nanoplates and nanodecahedra. In these processes, citrate ions were used as a morphology-controlled reagent and polyvinyl pyrrolidone as a capping agent. The growth process was evaluated by dynamic light scattering and ultraviolet/visible spectra measurements. The obtained silver nanoparticles (AgNPs) possessed various shapes, including triangular, truncated triangular, hexagonal and decahedron depending on the time duration of LED irradiation. Triangular nanoplates or decahedral nanoparticles (80–100 nm) were obtained when the silver colloid was exposed to green LED irradiation for different times (30 min—76 h). The average width and thickness of such nanoparticles were estimated to be approximately 80 nm and 20 nm, respectively. The technology uniqueness in this work is that we can change the morphology of silver from plate to decahedron via prolonging the LED illumination period from 140 min to 76 h instead of changing the light wavelength or temperature of the reaction solution. The surface-enhanced Raman scattering (SERS) experiment was carried out to measure Rhodamine 6G (R6G) concentrations plated on the silicon substrates. Silver nanodecahedra can detect the low concentration of R6G (10−8 M), while silver nanoplates can detect a higher R6G concentration of 10−6 M. Silver nanodecahedra could be used as an effective SERS substrate for ultrasensitive detection.

Reusable Plasmon-Decorated Chestnut-like Copper Oxide Nanostructures for SERS Sensing

Reusable plasmonic substrates are crucial for the development of biosensing applications using surface-enhanced Raman scattering (SERS), as they can provide unique advantages for ultrafast and accurate single-molecule recognition of different species. In this research, we employed thermally annealed cupric CuO and cuprous oxide Cu2O heterostructures to serve as highly stable nanotextured surfaces for designing robust 3D plasmonic biochips.Figure 1: Schematic representation of a research outline. Step 1 – controllable surface texturing by thermal annealing at oxygen-enriched atmosphere. Step 2 – plasmonic activation by ion spattering of Au/Pd alloy film. Step 3 – SERS performance monitoring by means of R6G dye fingerprint detection. Step 4 – Recovery test under ultra-fast mild cleaning in reactive oxygen/argon plasma. Step 5 – Simplified scheme of Rhodamine degradation inside plasma followed by the vanishing of the characteristic peaks in the Raman spectrum.Figure 2: (A-E) – SEM images showing the cuprous oxide Cu2O surface morphology altering with Au/Pd alloy thickening. (F) – Broadband Raman spectra representing vibrational features of chestnut Cu2O structures decorated by different plasmonic thicknesses together with ethanol diluted Rhodamine 10-5 M absorbed on the surface. (G) – Normalized intensity of the in-plane C-H bending vibrations of R6G 10-5 M as a function of bimetallic film thickness.The influence of bimetallic layer thickness on SERS performance has been studied for the chestnut patterned substrate. Figure 2 F depicts Raman spectra of Rhodamine used as a model biomarker (600-1800 cm-1) complemented by a signal originated from the Cu2O layers (100-800 cm-1). During Au/Pd film thickness reduction from 80 nm down to 20 nm, the R6G peak intensities undergo a gradual decrease, simultaneously, acoustic bands originated from Cu2O nanoparticles located in a range of 100-800 cm-1 become dominant. In accordance with Figure 2 G, that displays a signal intensity dropping for in-plane C-H bending vibrations as a function of bimetallic layer thicknesses, the analytical enhancement factor AEF acquires the following values: for 60 nm ~ 9.8×104, for 40 nm ~ 8.4×104 and for 20 nm ~ 1.1×104, respectively. The analogous finding was observed for Au decorated CuO nanoflakes, where EF increases with a noble metal film thickening [1]. Due to prominent anti-reflection properties, CuO/Cu2O heterostructures [2] appear to be an extremely suitable material for designing SERS-active substrates. Moreover, the high chemical inertness of Au/Pd alloy plasmonic layer allows a non-destructive substrate recovery with the assistance of reactive plasma species. Furthermore, the generation of reactive oxygen species-rich plasma by introducing oxygen gas into argon plasma drastically reduces cleaning session to less than 1 minute. For our best knowledge, this is the shortest recovery time for any 3D plasmonic SERS substrate reported in the literature. Additionally, results indicate that the nano-roughness is more important for achieving optimal plasmonic activity than micro-roughness. Overall, the designed chestnut-like Au/Pd@/Cu2O substrate is a ready-to-use chip that possesses a decent signal enhancement ~ 105 and reveals remarkable robustness under multiple plasma treatment showing nearly 100% of self-recovery with no degradation of a plasmonic layer. These findings are of great significance for the development of novel reliable SERS substrates with low-cost manufacture which can be utilised with great success in a wide area of plasmonic biosensing. REFERENCES [1] A. Balčytis, M. Ryu, G. Seniutinas, J. Juodkazyte, B. C. C. Cowie, P. R. Stoddart, M. Zamengo, J. Morikawa, S. Juodkazis, “Black-CuO: Surface-enhanced Raman scattering and infrared properties”, Nanoscale, 7, 43, October 2015, 18299-18304.[2] J. Yu, M. Yang, C. Zhang, S. Yang, Q. Sun, M. Liu, Q. Peng, X. Xu, B. Man, F. Lei, “Capillarity-Assistant Assembly: A Fast Preparation of 3D Pomegranate-Like Ag Nanoparticle Clusters on CuO Nanowires and Its Applications in SERS”, Advanced Materials Interfaces, 5, 19, July 2018, 1-8. Figure 1

Facile In Situ Photochemical Synthesis of Silver Nanoaggregates for Surface-Enhanced Raman Scattering Applications.

Recently, photochemical synthesis has attracted wide interest on in situ preparing the surface-enhanced Raman scattering (SERS) substrate with excellent performance, especially in a compact space and microfluidic channel. Herein, a facile, green and cost-effective approach to in situ photochemically synthesize silver nanoaggregates is demonstrated for SERS applications. By adjusting the photo-irradiation conditions, the morphologies and sizes of the silver nanoaggregates can be deliberately tailored. The synthesized silver nanoaggregates-based substrates exhibit a highly sensitive and reproducible SERS activity with a low detection limit of 10−8 M for 4-Aminothiophenol detection and relative standard deviation of 12.3%, paving an efficient and promising route for in situ SERS-based rapid detection in the environmental monitoring and food quality control.

Fabrication of Silver Nano-Dendrites on Optical Fibre Core by Laser-Induced Method for Surface-Enhanced Raman Scattering Applications.

In this work, we present a novel fabrication method for making the surface-enhanced Raman scattering (SERS) probe based on silver (Ag) nano-dendrites which are grown and deposited on the end of multi-mode fibre core by a simple and low-cost laser-induced technique. The morphology of the Ag-nanoparticles (AgNPs) could be controlled by the experimental conditions such as laser power, illumination time, and concentration of the reaction solution. The morphology and chemical composition of SERS fibre probes are characterized by high-resolution scanning electron microscope (HR-SEM) and Energy dispersive X-ray spectroscopy (EDX), respectively. These results confirmed how the Ag nanostructures morphology is modified as a function of illumination time of laser irradiation, and the growth and deposition of Ag nanostructures occur only in the main laser-irradiated part on the end of multi-mode fibre core. The achieved SERS-activity substrates on the fibre probes are testing with the detection of low concentration of Rhodamine 6G aqueous solutions in the range of 10-5-10-10 M. This study shows that SERS activity coupled with Ag nano-dendrites substrate on the fibre probe has the best enhancement factor of 1.93×107 for Rhodamine 6G due to the creation of many of hot-spots for amplifying Raman signals by Ag nano-dendrite structures, which is a promising candidate with low-cost SERS probe of chemical compact optical fibre sensors for direct, rapid, real-time and non-destructive detection of chemical compounds in liquid environment.

基于光热效应实现金纳米粒子的聚集及其SERS应用

基于光热效应实现金纳米粒子的聚集及其SERS应用

Controlling the Growth Locations of Ag Nanoparticles at Nanoscale by Shifting LSPR Hotspots.

Controlling chemical reactions by plasma is expected to be a new method for improving the structural properties of substrates. An Au nanojar array was prepared when Au was deposited onto a 2D polystyrene (PS) array. The site-selective chemical growth of Ag nanoparticle rings was realized around the Au nanojar necks by a local surface plasmon resonance (LSPR)-assisted chemical reaction. The catalytic hotspots in the nanostructure array could be controlled by both etching the nanojars and Au or TiO2 sputtering onto the nanojars, which were confirmed by the growth sites of the Ag nanoparticle in the LSPR-assisted chemical reaction. The structure of the nanojars and the electric field distributions of the growing nanoparticles were simulated and analyzed using Finite-Difference Time-Domain. FDTD simulations showed that the changes in the nanojar shape led to the changed hotspot distributions. At the same time, tracking the hotspot shifts in the process of structural change was also achieved by the observation of Ag growth. Nanoarray structure prepared by LSPR-assisted chemical reaction is one of the hot fields in current research and is also of great significance for the application of Surface-Enhanced Raman Scattering.